The National Treatment Agency for Substance Misuse has published new guidelines for doctors treating drug addicts.

It advises specialists on when and how they should prescribe heroin and methadone to patients.

It is expected to lead to hundreds more addicts being prescribed pharmaceutical heroin by doctors in specialist clinics across the country.

Last resort

Less than 500 people are currently prescribed heroin on the NHS - just 1% of heroin users in treatment.

Prescribing heroin is seen as a last resort and is generally only offered to those patients who have not responded to other treatments.

But ministers believe it is an important part of the range of treatments available to addicts.

They believe it can be used to help patients to manage their addiction and curb criminal behaviour.

Doctors believe that being able to offer heroin could also encourage more addicts to seek treatment on the NHS.

Many addicts are reluctant to seek treatment because they do not like or have not responded well to methadone in the past.

Doctors hope that being able to offer them heroin could change this.

Home Secretary David Blunkett has previously stated that he would support such a move.

Addressing a GPs conference in May, he said: "Prescribing heroin is all about what is right for the individual. It's about making it available to all those with a clinical need."

The charity DrugScope said it hoped more people will be prescribed heroin as a result of the guidelines.

Its chief executive Roger Howard said: "DrugScope hopes the guidelines will lead to the situation found in other countries where there is an increase in users potentially being prescribed heroin where other treatments have failed."